url and querystring Modules

These are two different modules, but they are related. The url module is used to parse and manipulate URLs. The querystring module is used to parse and manipulate query strings.

url Module

Let's start with the url module.

url.parse()

This method takes a URL string and returns an object. The object has properties for each part of the URL. The following code shows how to use this method:

const url = require('url');

const myURL = url.parse(
  'https://www.example.com/listing?id=1000&premium=true'
);
console.log(myUrl);

{
  host: 'example.com',
  port: null,
  hostname: 'example.com',
  hash: null,
  search: '?id=1000&premium=true',
  query: 'id=1000&premium=true',
  pathname: '/listing',
  path: '/listing?id=1000&premium=true',
  href: 'https://example.com/listing?id=1000&premium=true'
}

As you can see, we get a lot of information here. We can use this information to manipulate the URL.

url.format()

This method takes an object and returns a URL string. It is basically the opposite of url.parse(). The following code shows how to use this method:

const myURL2 = url.format({
  protocol: 'https',
  host: 'www.example.com',
  pathname: 'listing',
  query: {
    id: 1000,
    premium: true,
  },
});
console.log(myURL2); 

querystring Module

The querystring module is used to parse and manipulate query strings. Query strings are the options that you see in a URL after the ? character.

Let's create a variable with a query string with the year, month and day:

const myQueryString = 'year=2023&month=january&day=20';

querystring.parse()

Now, we can use the querystring.parse() method to parse the query string into an object:

const q = querystring.parse(myQueryString);
console.log(q.month, q.day, q.year); // january 20 2017

We can get the query string from the google url in the previous example:

const googleQuery = querystring.parse(myURL.search.slice(1));
console.log(googleQuery.q); // how to parse url nodejs

querystring.stringify()

We can use the querystring.stringify() method to convert an object into a query string:

const myQueryString2 = querystring.stringify({
  year: 2023,
  month: 'january',
  day: 20,
});

console.log(myQueryString2); // year=2023&month=january&day=20

So, both of these modules can be useful for certain tasks in certain applications.